Marylebone is walkable (or if you want to be quick, take a bus - its no time at all) from several other stations in the West End, including Euston, which is a nice walk across Regent's Park.
Use TfL's journey planner if you're unsure. It will tell you the exact bus stops and options across all modes of public transport.
https://tfl.gov.uk/plan-a-journey/

Hi guys, I've messaged Mark already but due to personal circumstances Jo and I won't be attending on Sunday so if anyone here wants to join the group and cheer on the Panthers, let Mark or I know. We both hope everyone has an enjoyable time watching Peyton crumble one last time! Jo is a diehard fan now thanks to you lot